import UIKit

var str = "Hello, playground"

/*
 第三章青铜挑战
 */
let population : Int = 13000
var mwssage: String = ""

if population < 10000 {
    mwssage = "镇上人口规模不大"
} else if population > 10000 && population < 20000{
    mwssage = "镇上人口规模大"
} else {
    mwssage = "镇上人口规模非常大"
}
print(mwssage)


/*
 第五章白银挑战
 */

let age = 25

if case 18...35 = age , age >= 21 , age < 30 {
    print("属于“酷人群”，到达了饮酒的年龄，不到30")
}






